Controlling the pKa of the bacteriorhodopsin Schiff base by use of artificial retinal analogues

Journal Article · Thu May 01 04:00:00 EDT 1986 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.83.10.3262· OSTI ID:5430135

Sheves, M; Albeck, A; Friedman, N; Ottolenghi, M

Artificial bacteriorhodopsin pigments based on synthetic retinal analogues carrying an electron-withdrawing CF3 substituent group were prepared. The effects of CF3 on the spectra, photocycles, and Schiff base pKa values of the pigments were analyzed. A reduction of 5 units in the pKa of the Schiff base is observed when the CF3 substituent is located at the C-13 polyene position, in the vicinity of the protonated Schiff base nitrogen. The results lead to the unambiguous characterization of the (direct) titration of the Schiff base in bacteriorhodopsin and to the conclusion that the deprotonation rate of the Schiff base during the photocycle (i.e., the generation of the M412 intermediate) is determined by a structural change in the protein.

• Research Organization: Weizmann Institute of Science, Rehovot, Israel
• OSTI ID: 5430135
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 10; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
BIOCHEMICAL REACTION KINETICS
CAROTENOIDS
CHEMICAL REACTIONS
ELEMENTS
HYDROCARBONS
IMINES
KINETICS
NITROGEN
NONMETALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PIGMENTS
PROTEINS
REACTION KINETICS
RHODOPSIN
SCHIFF BASES
STRUCTURE-ACTIVITY RELATIONSHIPS
SYNTHESIS
TERPENES